Ingo You're such a dingaling, I love you.
I'm all for and then horrendously against the idea of making a Dark/Fairy that's obviously meant to be creepy. For flavor purposes, I can see some notably wicked fae characters, like Morgan Le Fey, Maleficent or Madam La Pomme, or maybe even a prankster demigod that fell from grace being represented by that typing, but a lot of the meddling with humans starts to blend together at some point to where trying to ruin a mortal's life is just Child's Play to even the most random of magical creatures. Legends of driving somebody mad or killing a man who was seduced by a fairy doesn't really constitute gaining an edgy part Dark typing
when you see that every fairy and their godmother does that kind of stuff religiously.